Objective To observe the porcelain treated with Nd∶YAG laser irradiation and hydrofluoric acid (HF), and to explore the influence of integrated treatment of Nd ∶ YAG laser irradiation and HF etching in the bond strength of brackets to porcelain.Methods 48 metal ceramic prostheses were randomly divided into untreated control group,HF group,grooved treatment group,0.75W laser group,1.05W laser group,1.45W laser group. All samples were bonded to the brackets.After temperature cycling test,the shear bond strength (SBS)and tensile bond strength (TBS)were measured.Results There were significant differences in SBS and TBS between various surface treatment groups and untreated control group (P < 0.01).The SBS and TBS of brackets bonded in HF group was significantly higher than those in 1.05W laser and 1.45W laser groups (P <0.05).The SBS and TBS in 1.05W laser and 1.45W laser groups were higher than those in HF group (P <0.05).The SBS and TBS in 1.05W laser group were higher than those in other groups (P < 0.05).SBS showed positive correlation with TBS (r =0.426,P =0.000).Conclusion The use of Nd∶YAG laser irradiation with the energy parameter of 1.05W and HF could increase the bonding with formation of composite resin,and the more SBS,the more TBS.

OBJECTIVETo evaluate the influence of different surface treatments on porcelain surface topography.

METHODSMetal ceramic prostheses in 6 groups were treated according to the different surface treatment methods, and the surface topography was observed through scanning electron microscope (SEM). Group A was the control one (untreated), group B was etched by 9.6% hydrofluoric acid(HF), group C was deglazed by grinding and then etched by 9.6% HF, group D was treated with Nd: YAG laser irradiation(0.75 W) and HF etching, group E was treated with Nd: YAG laser irradiation (1.05 W) and HF etching, and group F was treated with laser irradiation (1.45 W) and HF etching.

RESULTSSurface topography was different in different groups. A lot of inerratic cracks with the shapes of rhombuses and grid, and crater with a shape of circle were observed on the ceramic surface after treatment with energy parameters of 1.05 W Nd: YAG laser irradiation and 9.6% HF etching (group E). Surface topography showed a lot of concaves on the inner wall of the cracks, and the concaves with diameter of 1-5 microm could be observed on the inner wall of the holes, which had a diameter of 20 microm under SEM.

CONCLUSIONThe use of Nd: YAG laser irradiation with the energy parameters of 1.05 W and the HF with a concentration of 9.6% can evenly coarsen the porcelain surface, that is an effective surface treatment method.

Ceramics ; Dental Bonding ; Dental Porcelain ; Hydrofluoric Acid ; Lasers, Solid-State ; Shear Strength ; Surface Properties

Peritoneal dialysis (PD) is the only well-established home-based dialysis therapy in Singapore. As it is a home-based modality, PD should be considered as a preferred mode of kidney replacement therapy (KRT) for patients with kidney failure during this COVID-19 pandemic as it avoids frequent visits to hospitals and/or satellite dialysis centres. The highly infectious nature of this virus has led to the implementation of the Disease Outbreak Response System Condition orange status in Singapore since early February 2020. This paper summarises the strategies for management of several aspects of PD in Singapore during this COVID-19 pandemic, including PD catheter insertion, PD training, home visit and assisted PD, outpatient PD clinic, inpatient management of PD patients with or without COVID-19 infection, PD as KRT for COVID-19 patients with acute kidney injury, management of common complications in PD (peritonitis and fluid overload), and management of PD inventory.
Ambulatory Care/methods* ; COVID-19/prevention & control* ; Home Care Services ; Hospitalization ; Humans ; Infection Control/methods* ; Pandemics ; Peritoneal Dialysis/methods* ; Self Care/methods* ; Singapore/epidemiology*